[sheepdog] [PATCH] sheep: add simple_store driver again

[Liu Yuan]

On 08/23/2012 10:58 PM, MORITA Kazutaka wrote:
> To fix this problem, we need to move stale objects in the worker
> thread.  I've spent several days trying to fix it, but it seems to
> need a lot of work, and it looks difficult to stable the change in a
> short time.
> 

Last time your patches to fix this problem looks kind of easy, why 'a lot
of work' now?


> $ ./farm.sh simple
> using backend simple store
>   Name        Id    Size    Used  Shared    Creation time   VDI id  Tag
>   test         1  100 GB  100 GB  0.0 MB 2012-08-23 11:29   7c2b25
> 
> real    0m1.016s
> user    0m0.092s
> sys     0m0.000s

This looks much better, but I think not good enough. If we have 500G data, it seems
that we still need around 5 minutes, which is unacceptable to guest VM too. For example
Linux guests won't tolerate for more than 2 minutes.

I think we really need to put the moving stale objects job to worker thread as a long-term fix,
which never block main thread. 

-- 
thanks,
Yuan